This nonprovisional application claims priority under 35 U.S.C. xc2xa7 119(a) on Patent Application No. 090133022 filed in Taiwan on Dec. 28, 2001, which is herein incorporated by reference.
1. Field of the Invention
The present invention relates to electronic packages, more particularly, to an assembly of a supporting substrate having passive components and a ball grid array (BGA) substrate with an integrated circuit chip on its surface.
2. Description of the Related Art
A ball-grid array (BGA) package is an illustrative example of a surface-mount package for an integrated circuit chip. Ball-grid array (BGA) packages house an integrated circuit (IC) chip that is either wire-bonded or flip-chip mounted to bond pads on the surface of an interposer. The interposer is generally a small circuit board or a semiconductor package for interfacing a circuit board.
In high-speed digital applications, electrical interconnections associated with the chip, the interposer, and the board interconnections of a BGA can exhibit electrical resonances and reflections that degrade signal integrity and electrical system reliability. Such degradations of signal quality generally increase with increasing signal frequencies or with digital signals that exhibit short rise times. Moreover, if power supply voltages are decreased to save energy, the detrimental affects on signal integrity may increase because of lowered electrical noise immunity.
In the past, passive components such as capacitors or resistors have been placed in the signal path to reduce or eliminate unwanted resonances and signal reflections. One method employed to eliminate the conventional problems is to provide passive components located on a large-scale printed circuit board (PCB). However, this method is not sufficient to eliminate the unwanted resonances and signal reflections. Also, another method employed to eliminate the conventional problems is to provide discrete passive components interposed in the BGA substrate. However, additional assembly complexity, and reduced circuit density are incurred with the use of discrete passive components. Therefore, improved integrated circuit packages capable of improving signal quality are needed.
An object of the present invention is to provide an integrated circuit package capable of improving signal quality. The passive component density of the integrated circuit package can be increased.
Another object of the present invention is to provide an integrated circuit package capable of improving signal quality. Accordingly, the passive components are closer to the ground layer and the power layer thus further eliminating the unwanted resonances and signal reflections.
Accordingly, the objects of the invention are attained by providing an integrated circuit package capable of improving signal quality. The integrated circuit package comprises a first substrate having a first surface and a second surface; an integrated circuit chip attached on the first surface of the first substrate; a plurality of external terminals mounted on the second surface of the first substrate; a plurality of first bonding pads mounted on the edge portion of the first surface of the first substrate and respectively connected to the corresponding external terminals; a second substrate having a first surface and a second surface facing the first surface of the first substrate; a plurality of second bonding pads mounted on the second surface of the second substrate and connected to the first bonding pads formed on the first substrate; and a plurality of passive components disposed on the first surface of the second substrate to connect to the second bonding pads wherein each of the second bonding pads connects to at least one of the passive components.
Furthermore, in this integrated circuit package, the second substrate is preferably ring-shaped or a supporting frame. Also, the passive components are capacitors or resistors.
Furthermore, in the integrated circuit package capable of improving signal quality, the passive components are preferably fastened on the first surface of the second substrate by a conductive adhesive or solder.
Furthermore, the integrated circuit package capable of improving signal quality can further comprise a power layer in the first substrate in which one of the first bonding pads is electrically connected to the power layer.
Also, integrated circuit package capable of improving signal quality can further comprise a ground layer in the first substrate in which one of the first bonding pads is electrically connected to the ground layer.
Furthermore, the first bonding pads are preferably fastened to the second bonding pads by a conductive adhesive or solder.
The integrated circuit package is characterized by using an additional supporting frame (second substrate) for passive components to mount on a plastic ball grid array (PBGA) substrate (first substrate).
Also, the passive components can be connected on the second substrate in a parallel connection thus further improving signal quality.